Treatment of vegetable fibers to separate and recover the fibrous and nonfibrous constituents



Patented Dec. 26, 1933 UNITED STATES TREATMENT OF VEGETABLE FIBERS T SEPARATE AND RECOVER THE FIBROUS AND NONFIBROUS CONSTITUENTS Adolf Hawerlander, St. Joseph, Mo., assignor to Albert D. Stewart, St. Joseph, Mo.; Hazel Stewart administratrix of said Albert D.

Stewart, deceased No Drawing. Application May 27, 1932 Serial No. 614,042

I 4 3 Claims. (01. 92 -1) This invention relates to the art of treating fibrous vegetable material to separate the fibrous and non-fibrous constituents, whereby the fibers are conditioned for felting or molding into fibrous 5 products such as paper, insulating building board and the like, while the non-fibrous constituent is recovered for use in the manufacture of numerous useful products.

It is an object of the present invention to proc- 1o ess fibrous vegetable material in such a manner and under such conditions as to recover for sub-' sequent utilization both the fibers and the nonfibrous constituents thereof. I

In one specific embodiment, the invention is directed to the processing of cereal straw, and

more particularly, wheat straw.

Cereal straw, such as rye, wheat, barley, oats, rice and corn, consists'of a large amount of cellulose fibers and a slightly less amount of non- 2o fibrous material, such as starch, sugar, gums, etc.

In the conditioning of the straw for the manufacture of paper, board and other fibrous products therefrom, it is common practice to separate, to

a more or less degree, the fibrous portion from the matural binder or gummy component that occurs in nature;

According to present practice, cereal straw is admixed with water or with an aqueous chemical and cooked or softened under various temperatures and steam pressures according to the requirements of the fibrous product to be manufactured from the conditioned straw. After cooking, the mixture is dumped into a stock or drainage pit where the surplus liquor is drained off and the disintegration of the binder or gummy component, which may have been incomplete in the digester, continues. drainage pit, the mixture is conveyed to beaters where the gummy-like binder is removed in aqueous solution by washers while the entire mass is agitated and circulated by the beater roll.

While the dissolved binder is being removed by the beaters, water is being continuously added at approximately the same rate, diluting the remaining solution and dissolving additional bind- After an interval in the er. Thisprocess is continuously carried on until operating the beater for relatively long periods of time.

3. The pollution of streams with the large quantity of waste solution.

4 The loss of large quantities of short fine fibers, especially toward the end of the washing process.

5. The loss of the non-fibrous component, which may be used in the manufacture of numerous useful products, such for instance, as. molding compositions, lacquers, saturants, binders and the like.

In one embodiment of the present invention, a' mixture of straw and solvent such as water, after having beein subjected to a softening or cooking treatment, is subjected to mechanical pressure to remove the greater part of the liquor or solu- I tion carrying the non-fibrous component in highly concentrated state.

In the instances wherelittle or no chemical is used in the softening or cooking treatment, a suitable means of grinding or crushing the straw may be interposed between the softening process and the mechanical pressure zone to facilitate the separation ofthe fiber and its binder in the squeezing or pressing which follows, such as a sence or in the presence of water and at normal or elevated temperature.

The broad concept of this invention comprises processing the fibrous vegetable matter in the presence of a solvent, such as water, steam or other vegetable solvent, to loosen and dissolve: the non-fibrous constituent and thereafter separating, by mechanical pressure, the solution of non-fibrous constituent from the fibrous con-, stituent.

According to one method of carrying out the invention, cereal straw, which generally is in bale form, is broken up and may be subjected to a cutting action for the purpose of separating the mass of straw into individual straws, and also for the purpose of shortening the length of the individm0 ual straws in order that in the softening or cook-. ing operation the straws may be more quickly and thoroughly agitated and be thereby more quickly, uniformly and thoroughly softened or cooked so that the gums and other non-fibrous components naturally associated with the straw may be loosened and dissolved in the solvent used during the softening or cooking operation. In this cutting operation the straw is individualized and the individual straws out to a length of from 11 two to five inches, more or less. This cutting operation is not essential and may be dispensed with.

The straw is charged to the digester or soaking vessel and a suitable amount of solvent added. Preferably, the amount of solvent introduced to the digester is limited to that which can be absorbed by the straw. After being charged with straw and solvent and, if desired, also with a chemical such as milk of lime, or the like, the digester or soaking vessel may be connected with a source of live steam of, say from 25 to pounds pressurefmore or less. at a temperature of approximately 275 to 300 F. The stock is agitated for from two to eight hours, the time of cooking or soaking being regulated relative to the temperature and amount of water used to that necessary to loosen said non-fibrous constituent.

It is important to note that too high a temperature may carbonize the natural gums and other non-fibrous constituent present in the straw and may render more difiicult separation of the nonfibrous constituent from the straw fibers during subsequent pressing.

Substantially the same result may be obtained by soaking straw in the presence of a solvent or in a chemical solution at either normal temperatures or with heat being applied, and not agitated. Conditions of manufacture in certain 10- calities may make this treatment desirable, and this simpler method of processing is included in the concept of my invention.

Where the fibers are to be used in the manufacture of a relatively thick insulating board or block it has been found preferable that the fibers be not'excessively softened. Therefore, in such instances, no chemical will be used. Where it is desirable to soften the fibers, for instance, where they are to be used in the manufacture of relatively thin paper or board, a suitable amount of chemical may be employed during the cooking or softening operation.

After the straw has been cooked or soaked for the proper length of time and under the desired conditions to soften and dissolve the non-fibrous constituent it is subjected to a mechanical pressing operation to separate the solvent containing the non-fibrous constituent from the fibrous component of the straw. In the mechanical pressing operation, any suitable type of instrumentality capable of separating the solvent from the fibers may be utilized, and it is not thought necessary to limit the invention to any particular type of apparatus. I have used a hydraulic press capable of exerting considerable pressure, and I have also used a ram and plunger type of press, as well as a screw type pulp dewatering press.

The water in the aqueous solution thus recovered may be evaporated to leave a non-fibrous residue. Evaporation of the water may take place by simple distillation at a temperature of say 100 C. at atmospheric pressure, to leave a heavy, viscous non-fibrous vegetable residue having the consistency of heavy molasses.

While I havenamed specific proportions, temperatures and the like in the foregoing specification, it is to be understood that I do not wish to be limited specifically to such figures, as the broad concept of the invention comprises the treatment of fibrous vegetable material to separate and recover the fibers and non-fibrous constituent.

Fibrous vegetable material contemplated for treatment according to the present invention includes in addition to the materials hereinbefore named, corn stalks, hemp, grasses and the like.

In the foregoing specification, I have described a process wherein the fibrous vegetable material is processed in the presence of a solvent to loosen and dissolve the non-fibrous constituent and thereafter subjected to mechanical pressure to separate and remove the non-fibrous constituent in solution in the solvent and recover the nonfibrous constituents. It is to be understood that the invention contemplates the attainment of the object of this invention either in one step, or

in two or more steps, that is, the original process- 1 ing and pressing step may be followed by a sec- 0nd processing and. pressing step, or even by a third or fourth processing or pressing step if necessary to facilitate the removal of a larger quantity of the non-fibrous material.

The non-fibrous constituents removed'during each processing and pressing step seem to have slightly different characteristics, and it may be desirable to keep the product of each separate processing and pressing step separate from the other. From a commercial standpoint it is, of course, entirely practical to keep the different solutions thus desired separate, and evaporate or dispose of the non-essential portions contained therein separately. For example, if evaporation is used to eliminate the water it is entirely practical to evaporate one solution at a temperature above 100 C. under pressure, using the vapor thus produced to vaporize the non-essential portions in a separate vessel either at atmospheric pressure or under vacuum.

I claim as my invention:

1. A process of treating fibrous vegetable material to separate and recover the fibrous and non-fibrous constituent, which comprises agitating said material with steam in a solvent to loosen and dissolve the non-fibrous constituent, thereafter separating by mechanical pressure the solution of non-fibrous constituent from the fibrous constituent, recovering said solution, evaporating the solvent and recovering the nonfibrous residue.

2. A process of separating and recovering the non-fibrous and fibrous constituent of cereal straw, which comprises subjecting said straw to a plurality of separate treatments with water to loosen and dissolve the non-fibrous constituent,

and intermediate said separate treatments separating by mechanical pressure the fibrous from the non-fibrous constituent, and separately recovering the solution from each pressing.

3. A process for treating fibrous vegetable materials to separate and recover the fibrous and non-fibrous components thereof, which comprises subjecting fibrous vegetable material containing natural non-fibrous components toan agitating action at an elevated temperature in the presence of water whereby to loosen and dissolve the non-fibrous components in said water, thereafter subjecting said mass to mechanical pressure to separate the aqueous solution containing the non-fibrous components from the fibrous components, and recovering the solution.

ADOLF HAWERLANDER. 

